1. Field of the Invention
The present invention relates to vibration damper for disk devices such as optical disk devices and magneto-optical disk devices which are used for acoustic equipment, video equipment, information equipment, various kinds of precision equipment, and the like regardless of whether they are mounted on vehicles or designed for household appliances. In particular, the present invention relates to a viscous fluid-filled damper adapted to damp vibrations of a supported body such as a mechanical chassis that is composed of a motor, an optical pickup, a disk table, and the like.
2. Description of the Related Art
As shown in FIG. 8 as an example, a disk device 1 is structured such that a disk 2 for recording and playback, such as an optical disk or a magneto-optical disk in a format of a CD or a CD-ROM, is horizontally chucked on a disk table 3, that the disk 2 is rotated integrally with the disk table 3 at a high speed, and that an optical pickup 4 approaches the disk 2 and tracks the disk 2 in a radial direction of the disk 2 to record data thereon and play back the contents thereof. A coil spring 7 joins a mechanical chassis 5 to a box body 6 of the disk device 1, and a viscous fluid-filled damper 8 is interposed between the mechanical chassis 5 and the box body 6, so the disk device 1 blocks off or damps vibrations transmitted from the outside.
As shown in FIG. 9, in the viscous fluid-filled damper 8 constructed as described above, a container body includes a stirring recess portion 12 made of a rubber-like elastic material protruding into the damper 8, a flexible portion 11 with a corrugated longitudinal cross-section which is deformed through vibrations, and a peripheral wall portion 10 made of a hard resin assuming a tubular shape. The viscous fluid-filled damper 8 is obtained by firmly fixing a lid body 9 made of a hard resin to the peripheral wall portion 10, filling an inner space enclosed by the container body and the lid body 9 with a viscous fluid 13 such as silicon oil, and filling in the viscous fluid. The viscous fluid-filled damper 8 is fitted to the disk device 1 by inserting a stirring shaft 14 provided on the mechanical chassis 5 serving as a supported body into the stirring recess portion 12 while inserting a screw 6b into a screw hole 9a bored through the lid body 9 and a screw hole 6a bored through the box body 6. Such the viscous fluid-filled damper is also disclosed in, for example, JP 2001-57068 A.
The viscous fluid-filled damper 8 shown in FIG. 9 is excellent in that the peripheral wall portion 10 made of the hard resin with a substantially tubular shape protrudes perpendicularly to the lid body 9 to ensure a volume for accommodating the viscous fluid 13 and guarantee shape stability of the container body. However, with the current tendency to reduce the thickness of the disk device 1, the viscous fluid-filled damper has also been required to have a further reduced thickness without deterioration in performance.